1. Field of the Invention
This invention relates to an information processing device, method thereof, and recording medium, and relates in particular to an information processing device, method thereof, and recording medium to provide information relating to moving or movement of the position for connecting on the network.
2. Description of the Related Art
Along with the spread of portable personal computers in recent years, personal computer users are now able to carry these personal computers around. Further, rather than just carrying these portable personal computers, users can also connect them to a network at their destination and receive services by way of the network.
In this kind of so-called mobile computing environment, a prerequisite for connecting the device (personal computer) to a network to receive services is that the node has mobility. This kind of node must be able to continue communication even if the node position changes.
Currently, Mobile IPv6 has been proposed as a method for node communication in an IPv6 mobile computing environment, based on IPv6 (Internet Protocol version 6) standards.
The node in Mobile IPv6 has two IP addresses respectively called the home address and the Care-of-Address. The Care-of-Address changes along with the movement of the node, according to the currently connected subnetwork. The home address is fixed regardless of node movement. The other node being communicated (or mating node) with, can communicate with the moving node regardless of the moving node position (currently connected subnetwork), by specifying the home address of the moving node.
The home agent is the node connected to the subnetwork for the node home address. When the node has moved, a binding update packet containing a new care-of-address is received from the node that moved, and the binding cache storing the home address and matching care-of-address is rewritten. The home agent notifies the network of the path information for the home address of the node that moved.
A drawing illustrating the procedure for registering the care-of-address is shown in FIG. 1. When the node constituted by terminal device 1 has moved, the terminal device 1 acquires the care-of-address from the subnetwork at the destination. The terminal device 1 issues a binding update packet containing authentication data for terminal device 1, a home address, and care-of-address and sends the binding update packet to the home agent 2.
A drawing describing the format of the IPv6 header for IPv6 packet is shown in FIG. 2. A four byte protocol version, an eight byte traffic class for identifying and grouping the priority, and a twenty bit flow label for identifying the packet requesting execution of a special operation by router are placed inside the IPv6 header. The source address constituting the address of the node that sent the packet, the destination address constituting the address of the node that received the packet, and an optional extension header are also placed inside the IPv6 header.
The IPv6 packet is hereafter referred to simply as a packet.
A drawing of the IPv6 packet format is shown in FIG. 3. The upper 64 bits of the IPv6 address are path information, and the lower 64 bits are interface identifiers for identifying the node network interface, within the subnetwork connected to the node. The interface identifiers signify a presence within the subnetwork, and addresses such as MAC addresses are used as interface identifiers. The IPv6 address is hereafter referred to simply as an address.
A drawing of the binding update packet of the related art is shown in FIG. 4. The care-of-address for terminal device 1 is set in the source address of the IPv6 header, and the home agent address is set in the destination address.
The home address of the terminal device 1 and data showing that this packet is updated are stored inside the extension header as the destination header.
A drawing describing the authentication header is shown in FIG. 5. An SPI (Security Parameters Index), sequence number and authentication data are contained in the authentication header. A home agent 2 determines items such as the authentication key and encryption formula by checking the SA (Security Association) based on the destination address and authentication header of the SPI as shown in FIG. 6.
The home agent 2 checks whether or not the authentication data (variable) is correct when the binding update packet is received. If the authentication data (variable) is determined to be correct, then the care-of-address contained in the binding update packet received in the binding cache is registered. The home agent 2 transmits a response packet to the terminal device 1.
Next, the procedure of the related art for sending a packet to terminal device 1 from a moving terminal device 3 is explained while referring to FIG. 7. The terminal device 3 inquires about the home address of terminal device 1 to the domain name server indicating the host name of terminal device 1. The domain name server 4 has stored the host name and home address match as shown in FIG. 8, so that the host address of terminal device 1 is searched for based on the host name and a reply made to the terminal device 3. The terminal device 3 generates and transmits a packet as shown in FIG. 9, having the home address of terminal device 1 set in the destination address.
The packet sent by the terminal device 3 arrives at the home agent 2 by the information path reported by home agent 2. As shown in FIG. 10, the home agent 2 further attaches an IPv6 header set with the care-of-address of terminal device 1 in the destination address to the receive packet, and transmits this packet. This packet arrives at terminal device 1 by the usual path management. The terminal device 1 removes from the received packet, the IPv6 header that was added by the home agent 2, and acquires the original packet.
The terminal device 1 generates a binding update packet containing the care-of-address of the terminal device 1 and the authentication header, and sends this binding update packet to the terminal device 3. Upon receiving the binding update packet, the terminal device 3 checks the authentication data and if the check shows the authentication data to be correct, the care-of-address of terminal device 1 is registered in the binding cache. The terminal device 3 transmits an acknowledge response packet to the terminal device 1.
The packet sent to the terminal device 3 from the terminal device 1, is set with a care-of-address for terminal device 1 as the source address as shown in FIG. 11, and the home address is stored in the destination options header of the extension header. This packet arrives in terminal device 3 by an optimal path.
After the binding update packet is received, as shown in FIG. 3, a routing header is attached to the packet the terminal device 3 transmits to the terminal device 1, and the packet arrives at the terminal device 1 by an optimal path.
When the terminal device 1 moves while in this status, the terminal device 1 transmits a new care-of-address to the terminal device 3 and the home agent 2. The terminal device 3 holds the matching home address of terminal device 1 and care-of-address as a binding cache. The terminal device 1 periodically transmits a binding update packet to the home agent 2 and the terminal device 3, and updates the binding cache in the terminal device 3.
The operation when the terminal device 1 has moved is described while referring to FIG. 13. The terminal device 1 acquires the care-of-address from the subnetwork at the (movement) destination. The terminal device 1 generates a binding update packet containing the home address of terminal device 1 shown in FIG. 14, and transmits this binding update packet to the terminal device 13. Upon receiving the binding update packet, the terminal device 3 checks whether or not the authentication data stored in the binding update packet is correct, and when the authentication data is determined to be correct, the care-of-address for the terminal device 1 stored in the binding update packet, is registered in the binding cache. The terminal device 3 returns the acknowledge response packet to the terminal device 1.
The terminal device 1 generates a binding update packet containing the home address of the terminal device 1 shown in FIG. 15, and transmits this binding update packet to the home agent 2. On receiving the binding update packet, the home agent 2 checks whether or not the authentication data stored in the binding update packet is correct, and when the authentication data is determined to be correct, the care-of-address for the terminal device 1 stored in the binding update packet, is registered in the binding cache. The home agent 2 returns the acknowledge response packet to the terminal device 1.
However, the related art is limited because a home agent 2 must be installed in the subnetwork for the home address of terminal device 1.
When the terminal device 3 does not hold the care-of-address for terminal device 1 as a binding cache, and a firewall is provided between the home agent 2 and terminal device 3, packets cannot be sent from terminal device 3 to terminal device 1.
In the same way, when a firewall is installed between the terminal device 1 and the home agent 2, the terminal device 1 cannot register the care-of-address in the home agent 2.
Further, when the home agent 2 is defective, or the link between the terminal device 1 and the home agent 2 is defective, the terminal device 1 cannot register the new care-of-address in the home agent 1.
When the terminal device 1 has moved, in the time interval until the binding cache of terminal 3 has been rewritten, the terminal device 3 transmits the packet with the care-of-address used prior to movement of the terminal device 1 so that the packet using the care-of-address prior to movement of terminal device 1, does not arrive at terminal device 1 and is lost.
When the terminal device 1 is positioned at the boundary of two wireless subnetworks, fluctuations occur in the radio wave intensity of the wireless subnetwork so that the terminal device 1 appears to be moving repeatedly back and forth between the two wireless subnetworks and a drastic increase in lost packets occurs.